We have the Quad Gamma pre and the Mastering Comp at our studio here in Halifax, Canada. Typically using the Gamma for kick, snare and overheads as well as electric guitars, and bass when possible, and vocals, and ..... Its the most instantly gratifying pre I have ever used. One could easily imagine Supertramp's "Crime of the Century" or AC/DC - "Back In Black" having been recorded with these.
The first thing I do with the pre is switch through the transformer options for the "less-than-subtle" options. I have found on occasion, that even the discrete (Jensen) path is more colourful than required, but that is rare indeed. Nickle transformer is often the end result for most occasions - it has a sweet saturation, not terribly aggressive, but adds a real sweetness and forward quality. Steel is quite aggressive and adds thicker harmonics but is never really ugly, just the right thing for wimpy sources or making anything rock harder. Sometimes I miss an output attenuator, but that's an easy fix in a chain.
The comp is relatively new to us and really hasn't spent much time off of the master buss! It's so refined, so ... something, that it is very difficult to make it sound bad. The first opto stage is somewhat "LA3A" but faster and is often the only stage used here. The second, discreet stage is apparently inspired by the 33609 (though I haven't had the pleasure) and is very versatile over a predetermined set of attack/release choices from 1.2 to limiting.
The routing switch options cover absolutely everything (except opto/discrete chain flip), allowing independent bypass of each comp, sidechain filter, stereo link, and a hardwire bypass of the entire unit.
The transformer options are again a pleasure to switch through and, on the master buss of an ITB mix, almost gives the impression of an analogue summing mixer (Shadow Hills makes a summing mixer too, the "Equinox", which I'm eager to hear). Sometimes the magic lies in routing signal through the transformers only.
The real joy using the comp or pre, is in the HUGE rotary switches. Beyond being able to recall settings exactly, there is a rewarding "mad scientist" feel to each unit.